In the field of cartoning machines it is known to handle tapered shape articles which substantially have a wider top portion and a narrower bottom portion (or vice-versa). Examples of such articles are cartons or tubs for food products or other products. One of the portions can have an opening lid, for example the known aluminium cover of yoghurt pots; some articles like the known coffee capsules can on the other hand be sealed. The use of these articles has increased significantly in recent years especially due to the contribution of coffee capsules facing a continuously increasing demand.
A conventional loading section of a cartoning machine generally comprises: an inlet area for articles delivered for example by a linear transporter; an article loading area for loading into boxes that are usually transported by a second conveyor; at least one robot or manipulator that operates between the inlet area and the article loading area. According to the prior art the robot picks up the articles from the first conveyor and places them directly in the boxes. In many applications the robot is a top loading robot equipped with a suitable grasping member, for example having a series of rods ending with vacuum-operated suction cups.
The cartoning (packaging) of articles with a tapered shape like the mentioned capsules, cups, etc. poses a series of problems that are not yet solved in a satisfactory manner.
In general, attempts are made to arrange these articles inside boxes forming rows in which upright articles (with the top portion facing upward) are alternated with articles flipped by 180 degrees (i.e. with the bottom portion facing upward), in order to optimise the use of the space in the box and consequently reduce costs for transportation and logistics. This arrangement is known as nesting of the articles and is generally applicable to articles which take up space in a substantially complementary manner when positioned side-by-side, for example articles of a different shape or articles of the same shape but with a different spatial orientation.
The arrangement however is not easy to obtain. The prior art includes efficient transportation systems which are able to form two parallel rows of articles flipping the articles of one row by 180 degrees with respect to the articles of the adjoining row. With a conventional top loading robot this arrangement would allow loading boxes with respectively upright and flipped rows of articles, but would not allow the nesting between one article and the other within the single rows.
In addition to this, the prior art suffers other drawbacks and limitations.
A first limitation is given by the fact that the loading section is substantially bound to the format of articles as available at the inlet area. For example the loading robot can only work efficiently with formats featuring a number of rows of articles being a multiple of the number of rows in the inlet area. Typically, the articles are made available to the loading robot on one or two tracks and with batches of articles aligned respectively in one or two parallel rows: in the second case (two rows or tracks) the loading robot works efficiently only with formats featuring an even number of rows of articles. Managing a format with an odd number of rows in the boxes would be impossible or in any case would impose a totally inefficient work cycle and a significant slowing of the loading capacity expressed in articles per minute. If the articles are rotated and alternated with each other it may be difficult for the robot to deposit a second group of products, since in order to reduce the space inside the boxes the tolerance between the rows is as small as possible, tending to zero.
Another limitation is given by the fact that there is a minimum transversal distance between the rows of articles below which the articles touch and interfere with one another. Therefore, in some applications and with simple top loading, which is nevertheless preferred for other reasons, it is not possible to compact the articles to the maximum extent. This drawback is felt in particular when the grouping available at the grasping area of the robot is different from the grouping desired in the boxes. For example, this is the case when the articles are available to the robot in a single-row arrangement (1×N) and must be loaded into the boxes in two parallel rows (2×N). In this case, the known loading robots with parallel-rods grasping head are unable to effectively pack together the articles to save space.
Moreover, the prior art systems are unsatisfactory when the required format has a plurality of levels or layers of articles stacked inside the boxes. In some conditions there is a need for a different arrangement of the articles of adjoining layers, for example the articles of a row of the second layer must be offset by one place with respect to the underlying row of articles of the first layer. This can be required both for reasons of space and to maintain the integrity of the articles: for example when cartoning coffee capsules it may be desirable to keep seal-to-seal contact and bottom-to-bottom contact, avoiding that a seal of a capsule is placed in direct contact with the bottom of another capsule.
The arrangement is difficult to obtain in the prior art: the arrangement of the input articles (i.e. made available to the robot) is substantially rigid, being the result of a series of upstream equipments, and is not easy or even impossible to change; complex formats are theoretically obtainable by intervening on the cycle of the loading robot or adopting different robots in parallel, but this solution would have the drawback of a high cost and/or unacceptable slowing down.
Summarizing, the prior art proves unsuitable for the needs of the field, especially for articles like coffee capsules where the most varied cartoning solutions are required with a great versatility. For the manufacturer of cartoning machines, all the above means the need for a specific design for each solution and a rigid approach that does not allow or strongly limits the economies of scale.